Google has quietly begun appending UTM parameters to outgoing links from Gemini, giving site owners and SEOs a reliable way to attribute traffic from the AI assistant for the first time. A Reddit user flagged the change in a thread titled "Google Gemini add UTM to results!" noting the behavior had appeared within roughly the previous 24 hours and comparing it to how ChatGPT already tags its links.

The change addresses a measurement gap that has frustrated analytics teams. Traffic from AI chatbots like Gemini frequently lands in the "direct" bucket in GA4, because "direct" is the fallback category analytics packages use when no referrer or UTM data explicitly ties a visit to a source.

Google acknowledges the change — and a referrer problem

Google Search Advocate John Mueller confirmed he observed the UTM tagging in the same Reddit thread, while raising a question about whether it was even necessary. "Nice. I see it too. Doesn't Gemini have a referrer too though? I thought you could already track them," Mueller wrote.

Redditor CrawlWarden supplied the missing context, and their numbers explain why the UTM addition matters more than the existing referrer alone:

"There is a referrer, but it mostly survives on desktop web only, reported pass through from the Gemini mobile app runs around 9 percent and Android assistant invocations strip it entirely, so a large share of that traffic has been landing in Direct instead of GA4's ai assistant medium. A UTM survives the in app webview and shows up in raw server logs too, which is why this matters more than it looks even though the referrer technically already existed."

Mueller responded by asking for reproducible evidence of the referrer loss: "If someone has more information on what happens with the referrer (ideally with something I can reproduce), I'm happy to forward that to the team. It would be great to have these retained (in addition to the UTM-tagging)."

That exchange is worth separating carefully. The UTM tagging itself is confirmed — Mueller sees it, multiple users report it, and the parameters are visible on outgoing links. The mobile referrer-loss figures, by contrast, come from community reporting (the roughly 9 percent pass-through rate on the Gemini mobile app and the claim that Android assistant invocations strip referrers entirely), not from a Google statement. Mueller's request for reproducible data signals Google has not verified that behavior internally, though his willingness to forward it to the team suggests the company is taking the report seriously.

Why the change lands now

The timing matters contextually. Publishers and site owners have voiced growing frustration over Google's AI features reducing the traffic Search sends to websites, with AI Overviews and Gemini absorbing queries that once produced clicks. In that environment, accurate measurement of how much traffic Gemini actually sends becomes a prerequisite for any informed judgment about AI channels — in either direction.

The practical benefits for SEOs and site owners are concrete:

• Accurate volume tracking. Gemini-referred visits stop disappearing into "direct," ending the guessing about how much traffic the platform sends.
• Segmentation and comparison. Analysts can isolate AI-referred visitors and compare them across AI referrers and against traditional search traffic.
• Budget justification. Real referral numbers make it possible to justify — or deprioritize — resource allocation to AI channels with data rather than assumptions.

What remains undocumented

The implementation leaves open questions. ChatGPT adds UTM parameters only to links tied to answers grounded in web sources — not to links generated from information in its training data, known as parametric knowledge. Google has not documented its own implementation, so nobody outside the company knows under what circumstances Gemini triggers the UTM tagging.

The reasonable assumption, absent documentation, is that Gemini adds the parameters when it presents answers in a format that directly references a website. That remains speculation until Google publishes details of the new behavior.

What to watch next

Site owners should check GA4 and raw server logs over the coming weeks for Gemini UTM-tagged traffic, and note whether the parameters survive in-app webviews consistently. The two open items worth monitoring: whether Google documents the trigger conditions for the tagging, and whether Mueller's team acts on the referrer-retention issue he offered to escalate.